Igor | ANATOMY OF THE OSMUNDACEAE 417 
SUMMARY OF OBSERVATIONS. 
1. An internal endodermis has been demonstrated in Osmunda 
cinnamomea, but in none of the other species examined. This inter- 
nal endodermis is in textural continuity with the external endo- 
dermis through branch gaps, and sometimes through foliar gaps. 
2. Internal phloem has been found in OQ. cinnamomea in the 
region of branching. This is continuous with the external 
phloem through ramular gaps. 
3. The external phloem of the Osmundaceae forms a contin- 
uous cylinder, a fact which De Bary has stated for O. regalis; 
and is not broken opposite the medullary rays as Strasburger 
has affirmed of the same species. Isolated sieve-tubes have 
been found in the medullary rays of O. cinnamomea. 
4. The xylem forms a cylinder broken only by foliar and 
ramular gaps. 
5. Brown sclerenchyma has been shown to be usually present 
in the medulla of QO. cinnamomea, not uncommonly in O. regalts, 
and not at all in O. Claytoniana. It occurs likewise in Todea 
barbara, but has not been observed in Z. superba. 
6. The medullary and cortical tissues of the Osmundaceae 
are histologically equivalent. Brown sclerenchyma, which is 
not an intrastelar tissue in other ferns, occurs in both medulla 
and cortex; and in O,. cinnamomea the brown sclerenchyma of 
the medulla is in continuity with that of the cortex. 
7. In O. cinnamomea the typical ramular gap is one through 
which internal and external ‘endodermis, internal and external 
phloem, cortex, and medulla connect. Every stage of degen- 
eration has been observed in Q. cinnamomea, however, down to 
the completely closed steles. O. regalis has a gap in the wood 
only, and O. Claytoniana usually none. 
8. The so-called “quergestreckte Zellen” pointed oo by 
DeBary in OQ. vegalis, and more fully described by Zenetti, have 
been found in all the species studied. They are sieve tubes, 
Possessing all the characteristic features of sieve tubes, even 
that of callus plugs. Their irregularity of orientation is shared 
by the other peripheral tissues of the central cylinder, and is 
